Umbrellas have been known and used for many years. Functionally, umbrellas most often are used to provide protection from precipitation, particularly rain. Umbrellas may also be used for protection from direct sunlight as in, for example, a parasol.
In addition to purely utilitarian functions, umbrellas have been designed for other uses. For example, U.S. Pat. No. 1,150,731 to Barcus describes a parasol on which fixed stars and constellations are marked as a guide to finding their location in the sky. However, Barcus's invention is fixed on a parasol such that the user views the markings on the outside of the parasol and compares it to the sky. There is not a simple way to incorporate the parasol into the night sky at the time of use. Thus Barcus' parasol is similar to a flat star map.
It is desirable to provide a star map which is easily and accurately lined up with the current night sky. It is also desirable to have a map which accurately depicts the full night sky without distortions or being only partially shown. Further, it is desirable to provide a star map which is portable and adjusts with the change in location while providing the same accuracy.